Plastic materials have been widely used for a variety of applications since they can be easily formed in a variety of shapes and, specifically, have been widely used as containers since they are light in weight as compared to metals and glasses.
When the plastic containers are used for containing viscous fluid substances such as ketchup, mayonnaise, paste, shampoo and liquid detergent, it is desired that these contents can be quickly and thoroughly discharged without adhering or remaining in the container. For this purpose, therefore, study has been conducted extensively, and there have been proposed various kinds of containers having excellent slipping property for such contents.
A patent document 1, for instance, is proposing a bottle of a multilayer structure including an innermost layer of an olefin resin that has an MFR (melt flow rate) of not less than 10 g/10 min.
The innermost layer of this multilayered bottle has excellent wettability for the oily content. Therefore, if the bottle is inverted or tilted, the oily content such as mayonnaise or the like falls down spreading along the surface of the innermost layer and is thoroughly discharged without adhering or remaining on the inner wall surface (innermost layer surface) of the bottle.
Further, patent documents 2 and 3 are proposing bottles of a polyolefin resin having an innermost layer that is blended with a saturated or unsaturated aliphatic amide as a lubricating agent.
The above patent documents 1 to 3 are all for improving the slipping property of the plastic containers for the content relying on the chemical composition of the thermoplastic resin composition that is forming the inner surfaces of the containers, and are achieving improvement in the slipping property to some extent. Due to limitations on the kinds of the thermoplastic resins and the additives that are used, however, there is a limit in improving the slipping property, and striking improvements have not been achieved yet.
Under such circumstances, therefore, a study has been forwarded from a physical point of view in an attempt to improve the slipping property. For instance, a patent document 4 is proposing a container in which hydrophobic fine oxide particles having an average primary particle diameter of 3 to 100 nm are adhered on the inner surface thereof.
According to the art proposed by the patent document 4, fine ruggedness is formed on the surface with which the content comes in contact and water-repelling property (hydrophobic property) is expressed by the finely rugged surface. That is, in addition to attaining the hydrophobic property of the material that is forming rugged surface, there is formed a pneumatic layer in the gaps in the rugged surface, the pneumatic layer exhibiting higher water-repelling property than that of the material that is forming the container. As a result, the aqueous content adheres much less to the container.
Here, the slipping property for the fluid contents is required not only by the containers but also by the pouring fittings as represented by a spout fitted to, for example, a bag-like container or a cap equipped with a pouring cylinder that serves as a pouring portion for pouring out the content.
The arts proposed in the above-mentioned patent documents 1 to 4 are all concerned to the containers but are not adapted to the pouring fittings. Besides, a further improvement has been desired concerning the slipping property for viscous fluid substances.
The present applicant has previously proposed a packing container in which at least part of the surface, with which the content comes in contact, permits a liquid to permeate through, and the liquid different from the content is held in the liquid-permeable surface (Japanese Patent Application No. 2012-199236). This technology gives very excellent slipping property for the content but is applied to the containers only.
Concerning the pouring fitting, further, the present applicant has previously proposed a pouring member having a pouring port for discharging a viscous fluid, wherein a hydrophobic layer of hydrophobic inorganic fine particles is selectively formed on an upper end surface of the pouring member (PCT-JP2012/080236). This technology, however, is still pursuing further improved slipping property.